Is rent I charge my adult son considered income?

Consider it cost sharing and not a business proposition. 

It depends.  If you are charging your adult son to share in household expenses, and/or there is no formal rental lease between you then you may not have to report it.  

If a profit motive is not what you are seeking but the rent charged is not really profitable see the information below for how to report the income.

The not-for-profit rental income is reported as follows and can be found in IRS Publication 527. 

Where to report. 

Report your not-for-profit rental income on Schedule 1 (Form 1040), line 8. If you itemize your deductions, include your mortgage interest and mortgage insurance premiums (if you use the property as your main home or second home), real estate taxes, and casualty losses from your not-for-profit rental activity when figuring the amount you can deduct on Schedule A.

Sign into your TurboTax account:

1. Click Tax Home  in the left panel
2. Click Wages & Income  > Review Income
3. Scroll down to Less Common Income. Click Show more
4. Start or Revisit Miscellaneous Income, 1099-A, 1099-C
5. Scroll to select  Other reportable income
6. Say Yes to Any Other Taxable Income?
7. Enter a description and amount